Our work is on gene expression in eukaryotic organisms and the mechanisms which control this expression. We are attacking this in 4 separate projects. Two projects deal with the mechanism of the termination of transcription in eukaryotes. We are determining the nucleotide sequence of the 3' end of the mRNA for the Z gene of Drosophila in the region just preceding the poly(A) tract to try to identify a termination or processing signal in the sequence. We are also trying to isolate a factor like rho from yeast and other eukaryotes. A third project deals with the control of actin synthesis in the sea urchin embryo and the time of appearance of different actin mRNAs during cleavage. We now have a variety of cloned sea urchin actin genes to be used as probes for determining actin mRNAs. We still need to identify these different actin genes. A fourth project deals with the same controls in the case of tubulin synthesis in the cleaving sea urchin embryo. For this project we are attempting to isolate tubulin genes from the library of sea urchin genes cloned in lambda charon 4A.